Blockade of purine metabolism reverses macrophage immunosuppression and enhances anti-tumor immunity in non-small cell lung cancer.

Aims: Immune checkpoint blockade therapy is not effective in most patients with non-small cell lung cancer (NSCLC) due to the immunosuppressive tumor microenvironment. Macrophages are key components of tumor-infiltrating immune cells and play a critical role in immunosuppression, which can be mediated by cell-intrinsic metabolism. This study aimed to evaluate whether macrophages regulate NSCLC progression through metabolic crosstalk with cancer cells and affect immunotherapy efficacy.

Methods: The macrophage landscape of NSCLC tissues were analyzed by single-cell sequencing and verified through flow cytometry and immunofluorescence. Multiplex assay, single-cell sequencing data, ELISA, immunofluorescence, and RNA-seq et al. were used to investigate and verify the mechanism of macrophage-mediated metabolic regulation on immunosuppression. The tumor-bearing model was established in C57BL/6 J mice to explore in vivo efficacy.

Results: We found that tumor tissue-derived macrophages exhibited an anti-inflammatory phenotype and had a prognostic value for NSCLC. NSCLC cell-secreted CXCL8 recruited macrophages from peritumor tissues to tumor sites and promoted programmed death-ligand 1 (PD-L1) expression by activating purine metabolism with increasing xanthine dehydrogenase and uric acid production. Moreover, purine metabolism-mediated macrophage immunosuppression was dependent on NLRP3/caspase-1/IL-1β signaling. Blockade of purine metabolism signaling enhanced anti-tumor immunity and the efficacy of anti-PD-L1 therapy.

Conclusions: Collectively, our findings reveal a key role of purine metabolism in macrophage immunosuppression and suggest that blockade of purine metabolism combined with immune checkpoint blockade could provide synergistic effects in NSCLC treatment.